struct Solution; impl Solution { pub fn climb_stairs(n: i32) -> i32 { let (mut ans, mut i) = ([2, 1], 3); while i <= n as usize { ans[i & 0b01] = ans[0] + ans[1]; i += 1; } ans[n as usize & 0b01] } } fn main() { print!("{}", Solution::climb_stairs(2)); }